1. Field of the Invention
The present invention generally relates to loom beams and methods of forming loom beams for use in glass fiber weaving operations. More particularly, the present invention relates to loom beams and methods of forming loom beams with resin compatible glass fiber yarns that are essentially free of slashing size using conventional slashing equipment.
2. Technical Considerations
In conventional glass fiber weaving operations, a glass fabric is woven by interweaving weft yarns (often referred to as xe2x80x9cfill yarnsxe2x80x9d) into a plurality of warp yarns. Generally, this is accomplished by positioning the warp yarns in a generally parallel, planar array on a loom, and thereafter weaving the weft yarns into the warp yarns by passing the weft yarns over and under the warp yarns in a predetermined repetitive pattern. The pattern used will depend upon the desired fabric style.
Warp yarns are typically formed by attenuating a plurality of molten glass streams from a bushing or spinner. Thereafter, a coating (or primary size) is applied to the individual glass fibers and the fibers are gathered together to form a strand. The strands are subsequently processed into yarns by transferring the strands to a bobbin via a twist frame. During this transfer, the strands can be given a twist to aid in holding the bundle of fibers together. These twisted strands are then wound about the bobbin and the bobbins are used in the weaving processes.
Positioning of the warp yarns on the loom is typically done by way of a loom beam. A loom beam comprises a specified number of warp yarns (also referred to as xe2x80x9cendsxe2x80x9d) wound in an essentially parallel arrangement (also referred to as xe2x80x9cwarp sheetxe2x80x9d) about a cylindrical core. Loom beam preparation typically requires combining multiple yarn packages, each package comprising a fraction of the number of ends required for the loom beam into a single package or loom beam. For example and although not limiting herein, a 50 inch (127 cm) wide, 7628 style fabric which utilizes a G75 yarn input typically require 2204 ends. However, conventional equipment for forming a loom beam does not allow for all of these ends to be transferred from bobbins to a single beam in one operation. Therefore, multiple beams comprising a fraction of the number of required ends, typically referred to as xe2x80x9csection beamsxe2x80x9d, are produced and thereafter combined to form the loom beam. In a manner similar to a loom beam, a section beam typically includes a cylindrical core comprising a plurality of essentially parallel warp yarns wound thereabout. While it will be recognized by one skilled in the art that the section beam can comprise any number of warp yarns required to form the final loom beam, generally the number of ends contained on a section beam is limited by the capacity of the warping creel. For a 7628 style fabric, four section beams of 551 ends each of G75 are typically provided and when combined offer the required 2204 ends for the warp sheet, as discussed above.
As previously discussed, a primary sizing composition is applied to the glass fibers, typically immediately after forming. Traditionally, the filaments forming the continuous glass fiber strands used in weaving fabric are treated with an aqueous starch-oil sizing, which typically includes partially or fully dextrinized starch or amylose, hydrogenated vegetable oil, a cationic wefting agent, emulsifying agent and water, as is well known to those skilled in the art. For more information concerning such sizing compositions, see K. Loewenstein, The Manufacturing Technology of Continuous Glass Fibres, (3d Ed. 1993) at pages 237-244 (3d Ed. 1993), which is specifically incorporated by reference herein. While such sizings are generally robust enough to provide protection to the fibers during fiber forming and loom beam manufacturing processes, they normally are unable to protect the glass fibers, and in particular the warp yarn fibers, from abrasion and wear during high speed weaving. As a result, it is conventional practice in the textile weaving industry to pass the warp yarn through a slasher, which applies a slashing size to the warp yarns during the manufacture of the loom beam to provide the additional protection required, in a manner to be discussed later in more detail. More particularly, the slashing operation provides the vehicle to add additional film forming chemistry to the fibers forming the warp yarn sheet. Typically, the slashing size includes either fully or partially hydrolyzed polyvinyl alcohol (PVA) materials and is a mixture in the 6-8% solids range with a viscosity of 15 to 20 centipoise (CPS). The slashing size is typically applied by submerging the warp yarn sheet in a vessel containing the slashing size via a series of submersion rollers and then passing it through a squeeze roll system, which typically exerts 15 to 20 pounds per square inch of squeezing pressure on the coated yarn in addition to the dead weight of the squeeze roller (the squeeze pressure can vary due to yarn diameter), to remove the excess slashing size. The slashing size can be applied at an elevated temperature, e.g. in the range of 130 to 150xc2x0 F. (54 to 66xc2x0 C.) or at room temperature, depending upon the recommendations of the PVA producer. After squeezing the excess size from the yarn sheet, the slashing sized sheet is dried in any convenient manner known in the art, such as but not limited to passing the sheet over heated rollers and/or through a hot air drying oven. In a slasher incorporating heated rollers, or cans, the surface temperature of the cans is typically in the range of 240 to 280xc2x0 F. (116 to 138xc2x0 C.). The actual temperature profile of the drying cans depends in part on the can arrangement, number of cans, and yarn speed. In a hot air drying oven, the air temperature within the oven typically ranges from 275 to 300xc2x0 F. (135 to 149xc2x0 C.). After drying, the warp yarn sheet passes through a series of split rods to separate the warp sheets and through a hook reed assembly and comb to combine the warp sheets and assure that no ends are adhered to each other. The yarn sheet is then wound onto the loom beam.
Both the primary starch-oil coating and slashing size are not compatible with polymeric resin matrix materials used to impregnate woven fabric incorporating the coated yarns. As a result, these coatings must be removed from the fabric, e.g. by heating cleaning and/or scrubbing, prior to incorporation of a fabric woven from these yarns into the matrix material. For example, a typical one-step heat cleaning process can entail heating the fabric at 600 to 800xc2x0 F. (316 to 427xc2x0 C.) for 70-80 hours to remove the starch-oil primary size and slashing size. In an alternative two-step operation, the fabric is unrolled through an oven where it is exposed to a flame that burns off a portion of the sizes, and then heated 600 to 800xc2x0 F. (316 to 427xc2x0 C.) for 50 to 60 hours. The first step of this two-step operation is sometimes referred to as caramelizing and is typically used to heat clean fabrics woven from coarse yarns, i.e. 7628 style fabric.
When a primary size that is compatible with the resin matrix material is applied to the individual glass fibers during forming, it has been found that the application of additional slashing size to protect the glass fibers is unnecessary. As a result, the need for additional fiber protection through the application of a slashing size is eliminated. However, it has been observed that when such warp yarns having a resin compatible coating are simply wound onto a loom beam from multiple section beams, for example by passing the warp yarn through a slasher without the addition of slashing size, heating and drying (sometimes referred to as xe2x80x9cdry slashingxe2x80x9d) to form a loom beam, the number of loom beam defects, such as end breaks due to rolled and twisted ends, is excessive. Rolled ends, which is a condition wherein adjacent glass strands roll on top of each other and are twisted together, are particularly troublesome as they can lead to end breaks during weaving, which in turn are associated with fabric quality issues such as ends out, fuzzy ends, chaffed ends, and undesirable yarn splices.
Nevertheless, the capability to make loom beams with warp yarns having a resin compatible coating on a slasher without using slashing size is important since the main method of forming loom beams in the textile weaving industry is by use of a slasher and most weaving operations already have this type of equipment. As a result, it would be advantageous to provide a process whereby a loom beam can be made with yarn having a resin compatible coating using a slasher, but without the need for slashing size.
The present invention provides a method of forming a loom beam comprising: (A) unwinding at least one warp yarn from at least one section beam comprising a plurality of warp yarns, wherein the at least one warp yarn comprises at least one fiber comprising a resin compatible coating on at least a portion of a surface thereof; (B) applying heat to the at least one fiber; and (C) winding the at least one warp yarn with the at least one fiber onto a loom beam, wherein the at least one fiber on the loom beam is essentially free of slashing size. In one nonlimiting embodiment of the invention, positioning comprises positioning a plurality of section beams, each comprising a plurality of warp yarns, and at least one warp yarn of each section beam comprises at least one glass fiber comprising a resin compatible coating on at least a portion of a surface thereof.
The present invention also provides a method of forming a loom beam comprising: (A) unwinding at least one warp yarn from at least one section beam comprising a plurality of warp yarns, wherein the at least one warp yarn comprises a resin compatible coating on at least a portion of a surface thereof; (B) applying heat to the at least one warp yarn; and (C) winding the at least one warp yarn onto a loom beam, wherein the at least one warp yarn on the loom beam is essentially free of slashing size.
The present invention further provides a method of forming a loom beam comprising: (A) positioning at least two section beams at a slasher, each section beam comprising a plurality of warp yarns, wherein at least one warp yarn of each section beam comprises at least one glass fiber comprising a resin compatible coating on at least a portion of a surface thereof; (B) passing the at least one warp yarns through the slasher; (C) applying heat to the at least one warp yarns while passing the at least one warp yarns through at a portion of the slasher; and (D) combining the plurality of warp yarns from the section beams to form a loom beam, wherein the at least one warp yarns on the loom beam are essentially free of slashing size.
The present invention also provides a loom beam comprising: (A) a center roll; and (B) a plurality of warp yarns wound around the center roll, wherein at least one of the warp yarns comprises at least one fiber comprising a resin compatible coating on at least a portion of a surface thereof, and the at least one fiber is essentially free of slashing size. In one nonlimiting embodiment of the invention, the plurality of warp yarns each comprise a plurality of glass fibers comprising a resin compatible coating on at least a portion of a surface thereof, and the plurality of glass fibers are essentially free of slashing size.
The present invention further provides a loom beam comprising: (A) a center roll; and (B) a plurality of warp yarns wound around the center roll, wherein at least one of the warp yarns comprises a resin compatible coating on at least a portion of a surface thereof and is essentially free of slashing size.